Single CellProtein

Presented By:Shraddha Bhatt

PhD (Agri. Micro)AAU, Anand.

Any of a group of complex organic macromolecules that contain carbon, hydrogen, oxygen, nitrogen, and usually sulphur and are composed of one or more chains of amino acids.

Proteins are fundamental components of all living cells and include many substances, such as enzymes, hormones, and antibodies, that are necessary for the proper functioning of an organism.

They are essential in the diet of animals for the growth and repair of tissue and can be obtained from foods such as meat, fish, eggs, milk, and legumes.

What is Protein ???

In inactive lifestyle, the recommended dietary

allowance (RDA) for a sedentary individual is

about 0.8 grams per kilogram of body .

So, if weight of body is 90 kg then protein

requirement

90 x 0.8 = 72g per day protein is required.

If lifestyle is active or hard working then protein

required is 1.4g/kg to 1.8 g/kg of body weight daily.

Protein requirement:

Essentials amino acids

FAO recommendation Minimum

Phenylalanine 2.2 1.1Methionine 2.2 1.1

Leucine 2.2 1.1Valine 1.6 0.8Lysine 1.6 0.8

Isoleucine 1.4 0.7Threonine 1.0 0.5

Tryptophan 0.5 0.25Total 12.7 6.35

Daily requirements (g) of essential aminoacids for the human adult Data retrieved from FAO (http://www.fao.org)

The increasing world deficiency of protein is becoming a main problem of humankind. Since the early fifties, intense efforts have been made to explore new, alternate and unconventional protein. For this reason, in 1996, new sources mainly yeast, fungi, bacteria and algae named Single Cell Protein (SCP) as coined to describe the protein production from biomass, originating from different microbial sources. Microbial biomass has been considered an alternative to conventional sources of food or feed.

Large-scale processes for SCP production show interesting features, including:

The wide variety of methodologies, raw materials and microorganisms that can be used for this purpose

High efficiency in substrate conversion High productivity, derived from the fast growth rate of

microorganisms Independence of seasonal factors (Roth, 1980; Parajo et al., 1995)

Introduction

A survey of the history of the use of microorganisms for human consumption indicates three major trends:

(a) microbes as a source of enzymes in the food industry (baking,

brewing, distilling, wine making, cheese production) has at

present a new aspect-the use of immobilized enzymes of microbial

origin,

(b) microbes as producers of nutritive substances (amino acids,

nucleotides, vitamins, organic acids, sugars, aromatizers) and

(c) direct utilization of microbial biomass as foodstuff.

History

Since 2500 B.C. yeasts have been used in bread and beverage production. In 1781 processes for preparing highly concentrated forms of yeast were established.

"Food from oil"In the 1960s, researchers at British Petroleum developed what they called "proteins-from-oil process": a technology for producing single cell protein by yeast fed by waxy n-paraffins, a product produced by oil refineries. Initial research work was done by Alfred Champagnat at BP's Lavera Oil Refinery in France; a small pilot plant there started operations in March in 1963, and the same construction of the second pilot plant, at Grangemouth Oil Refinery in Britain, was authorized.The term SCP was coined in 1966 by Carol L. Wilson.The "food from oil" idea became quite popular by the 1970s, with Champagnat being awarded the UNESCO Science Prize in 1976, and paraffin-fed yeast facilities being built in a number of countries.

Advantages of SCP over conventional protein sources are:

It has high protein and low fat content. It is good source of vitamins particularly B-complex. e.g. Yeasts It can be produced through-out the year. Waste materials are used as substrate for the production of these proteins. It reduces the environmental pollution and helps in recycling of materials. SCP organisms grow faster and produce large quantities of SCP from relatively small area of land and time. These have proteins with required amino acids that can be easily selected by genetic engineering. During the production of SCP biomass, some organisms produce useful by products such as organic acids and fats. It can be genetically controlled. It causes less pollution. Algal culture can be done in space which is normally unused.

Kharatyan (1978)

All single-celled microorganisms of interest from the industrial point of view have a nondigestible envelope, which makes protein assimilation difficult.The content of nucleic acids in the unicellular biomass is higher than the permissible level and may cause disorders of purine metabolism in the human body.The biomasses of some unicellular microorganisms have an unpleasant color (algae), taste, and smell, which make them unsuitable even for animal consumption.Food grade production of SCP is more expensive than othersources of proteins, as it depends on the raw materials.SCPfor human consumption is 10-12 times more expensive thanSCP for animal feed.Digestion of microbial cells is rather slow, and is frequentlyassociated with indigestion and allergy reactions.

Factors that impairs the usefulness of Unicellular biomass

1) Microbial screening: with microbial screening, in which suitable production strains are obtained from samples of soil, water, air or from swabs of inorganic or biological materials and are subsequently optimized by selection, mutation, or other genetic methods.

2) Suitable raw material

3) Process engineering:Then the technical conditions of cultivation for the optimized strains are done and all metabolic pathways and cell structures will be determined

4) Apparatus technology: adapt the technical performance of the process in order to make the production ready for use on the large technical scale.

5) Economic factors : Energy , Cost6) Safety demands & Environmental protection ( to the process and to the product)7) Legal and controlled aspects (Operating license & product authorization)

SCP Manufacturing Protocol

“Possible Substrates for SCP”

They can be subdivided into three categories: high energy sources (natural gas, n-alkanes, gas-oil, methanol, ethanol, acetic acid); different wastes (molasses, sulfite waste liquor, milk, whey, fruit wastes); and renewable plant resources (sugar, starch, cellulose).The interest in methanol and ethanol as a raw material for SCP is based on;1) complete water solubility of these alcohols and 2) the possibility of washing cells completely free of residual methanol or ethanol;3) the high purity of the substrate (99.5%);4) the relative cheapness of the substrate;5) the restricted utilization of the substrates by microorganisms, thus reducing the

probability of contamination; 6) easy and simple storage and maintenance; and7) lower requirements for oxygen during fermentation and lower requirements for

energy during cooling as compared with microbial cultivation on hydrocarbons.

Average composition of the main groups of micro-organisms (% dry weight)

Fungi Algae Yeasts BacteriaProtein 30-45 40-60 45-55 50-65

Fat 2-8 7-20 2-6 1.5-3.0

Ash 9-14 8-10 5-9.5 3-7

Nucleic Acids

7-10 3-8 6-12 8-12

TABLE : 1

Miller et al., (1976)

Safety Usefulness

Ease of processing Rate of growth

Cultivation conditions

Parameters to be considered during selection of microorganisms as protein source:

1. Yeasts and FungiFilamentous Fungi used for SCP production are Chaetomium celluloliticum, Fusarium graminearum, Paecilomyces varioti which grows on cellulose waste, starch, and sulphite waste liquor respectively and content about 50 – 55 % protein.

SCP is produced from yeasts viz. Candida utilis, Candida lipolytica, Saccharomyces cervicea.Torula yeast (which grows on Ethanol) as a food is obtained through fermentation using molasses as substrate and it has high protein–carbohydrate ratio than forages. It is rich in lysine but poor in methionine and cysteine. Saccharomyces consists of high protein with good balance of amino acids and rich in B–complex vitamins. It is more suitable as poultry feed.Yeast are higher in lysine content.Strict aseptic conditions are required when using Yeast as a SCP production.

Disadvantages: High nucleic acid content.

Slow growth is observed in Fungi vis-à-vis than yeast & bacteria.Contamination risk.Mycotoxins are also produced.

2. Bacteria They have more than 80% protein but are poor in sulphur containing amino acids. Brevibacterium uses hydrocarbons while Methylophilus methylitropous uses methanol as a substrate.

Disadvantages: It has high nucleic acid content.

Recovering the cells is a bit problematic. Endotoxin production should be carefully tested.

3. Algae: Chlorella, Scenedesmus acutus and Spirulina maxima are grown for SCP. These have about 60% protein with good amino acid composition but less in sulphur containing amino acids. Chlorella and Spirulina are used for commercial scale production in Taiwan, Thailand, Japan, Israel, Mexico and USA. It is spray dried and sold as pills and powders.

Disadvantages: As they are rich in Chlorophyll, it is not advised for human consumption (except Spirulina). It has low density i.e. 1-2 gm dry weight/litre of substrate. There is lot of risk of contamination during growth.

The United Nations Organization(UNO) in its World Food Conference of 1974 declared Spirulina as the best food for tomorrow.World Health Organization(WHO) has hailed Spirulina the greatest super food on the earth.Upon testing it NASA scientists found 1 kg of Spirulina nutritionally equal to 1000 kgs of assorted vegetables

At Murugappa Chettiar Research Centre (MCRC, Madras) food-grade spirulina is cultivated

and the products are distributed to the local undernourished children.

The Nutritional Values of Elken Spirulina Nutritional value is 14 times higher than cow’s milk.Excellent source of quick supply of glucose to the blood.Contains over 13 types of vitamins and is the richest vegetative source of B12 in the world.Excellent source of minerals (more than 13 types of minerals).Contains 4 types of natural pigments including beta caroteneContains all the 8 essential amino acids.Complete in nutritional value that it is used as food for astronauts.

It is recognised a safe and nutritious food source by:

UN Food & Agricultural Organisation (FAO)World Health Organisation

Certified free of microcystins (Health Canada)

Microorganism Substrate Used as Used commerciallyAlgae Chlorella sp. CO2 + sunlight Feed Yes (Japan and Taiwan)

Scenedesmus acutus CO2 + sunlight -

Spirulina maxima CO2 + sunlight Feed Yes (Mexico)Yeasts

Candida utilis (Torula Yeast) 1. Confectionery - Yes (U.K.), Symba process

2. Ethanol Feed Yes (USA) 3. Sulphite liquor - Yes (Europe, USA, Russia)

C. intermedia Whey - Yes; Vienna processC. krusei (+ Lactobacillus bulgarius) Whey - Yes; Kiel process

C. lipolytica n-alkanes (C10 - C23) + ammonia - Yes (Russia)

Kluyveromyces fragilis Whey Food Yes (France); Le Bel process

Saccharomyces cerevisiae Molasses (Food)* YesFungi

Chaetomium cellulolyticum Cellulosic wastes - Promising

Fusarium graminearum Starch hydrolysate Yes (U.K)

Paecilomyces varioti Sulphite liquor - Yes (Finland); Pekilo process

Bacteria Brevibacterium sp. C1 - C4 hydrocarbons - Process developed

Methylophilus methylotrophus Methanol Feed Yes (U.K.),

Properties of SCP

One of the main advantages of SCP compared to other types of protein is the small doubling time of cells (td) as shown in Table

Organism Mass DoublingBacteria and yeast 10-120 min

Mold and Algae 2-6h

Grass and some plants 1-2wk

Chickens 2-4 wk

Pigs 4-6 wk

Cattle 1-2 mo

People 0.2-0.5 yrs

TABLE : 2

Efficiency of protein production of several protein sources in 24 hours (16)

 

Due to this property, the productivity of protein from micro-organisms is greater than that of

traditional proteins

Organism(1,000 kg)

Amount of Protein

Beef Cattle 1.0 kgSoybeans 10.0 kg

Yeast 100.0 tnBacteria 100x10,000,000 tn

TABLE : 3

Bacterial protein is similar to fish protein, yeast's protein resembles soya and the fungi protein is somewhat lower than the yeast's. Of course microbiological proteins are deficient in the sulphur amino acids cysteine and methionine and require supplementation, while they exhibit better levels of lysine.

Essential amino acid content of the cell protein in comparison with several reference proteins

(grams of amino acid per 100 grams of protein)

Amino Acids

Cellulomonas

Saccharomyces

cerevicia

Spirulina maxima

PeniciIllium

notatum

Wheat Egg Cowmilk

Lysine 7.6 7.7 4.6 3.9 2.8 6.3 7.8

Threonine 5.4 4.8 4.6 - 2.9 5.0 4.6

Methionine 2.0 1.7 1.4 1 1.5 3.2 2.4

Cysteine - - 0.4 - 2.5 2.4 -

Tryptophan - 1.0 1.4 1.25 1.1 1.6 -

Isoleucine 5.3 4.6 6.0 3.2 3.3 6.8 6.4

Valine 6.5 3.9 5.4 3.9 4.4 7.4 6.9

Phenylalanine 4.6 4.1 5.0 3.9 4.4 7.4 6.9

Histidine 7.8 2.7 - 2.8 2.0 6.3 4.9

Arginine 6.4 2.4 - - 4.8 - -

TABLE : 4

Other nutritional parameters which evaluate the quality of a given SCP are:

- the digestibility (D)- the biological value (BV)

- the protein efficiency ratio (PER)- the net protein utilisation (NPU)

The quality of SCP is an important factor for commercial production.

1. First parameter which reflects the quality of a protein, is the is the percentage of the total nitrogen Digestibility Coefficient consumed which is absorbed from the digestive tract.

2. Estimation of the Biological Value (BV) is a measure of nitrogen retained for growth or maintenance.

3. An accurate method to evaluate the quality of proteins is the determination of the Protein Efficiency Ratio (PER), expressed in terms of weight gain per unit of protein consumed by the test animal in short-term feeding trials.

4. Finally, the Net Protein Utilization (NPU) -equivalent to the calculation BVxDC-is a measure of the digestibility of the protein and the biological value of the amino acids absorbed from the food.

Source Nitrogen(%)

Crude Protein(%)

Filamentous fungi 5-8 31-50Algae 7.5-10 47-63Yeast 7.5-8.5 47-53

Bacteria 11.5-12.5 72-78Milk 3.5-4.0 22-25Beef 13-14.4 81-90Egg 5.6 35Rice 1.2-1.4 7.5-9.0

Wheat Flour 1.6-2.2 9.8-13.5Corn meal 1.1-1.5 7.0-9.4

TABLE : 5

Nitrogen and Protein contents of microbial cells compared with selected foods of animal and plant origin

Kharatyan(1978)

About 70-80% of the total cell nitrogen is represented by amino acids while the rest occurs in nucleic acids. This concentration of nucleic acids is higher than other conventional proteins and is characteristic of all fast growing organisms. The problem which occurs from the consumption of proteins with high concentration of nucleic acids (78 g/100 g protein dry weight) is the high level of uric acid in the blood, sometimes resulting in the disease gout. Uric acid is a product of purine metabolism. Most mammals, reptiles and molluscs possess the enzyme uricase, and the end product of purine metabolism is allantoin.Man, birds and some reptiles lack the enzyme uricase and the end product of purine degradation is uric acid. The removal or reduction of nucleic acid content of various SCP's is achieved with one of the following treatments: chemical treatment with NaOH; treatment of cells with 10% NaCl; thermal shock.These methods aim to reduce the RNA content from about 7% to 1% which is considered within acceptable levels. A 30 min stand at 64°C reduces intracellular RNA levels in Fusarium graminearum from 80mg/g to 2mg/g

Problem of Nucleic Acids

Cell wall destruction:Non Mechanical Methods:

1. Chemical treatment: acid, base, solvent, detergent

2. Enzyme analysis: lytic enzymes, phage infection, auto lysis

3. Physical treatment: freeze- thaw, osmotic shock, heating and drying.

Mechanical Methods:

4. High pressure homogenization

5. Wet milling

6. Sonification

7. Pressure extrusion: French press,

8. Decompression (pressure chamber)

9. Treatment with grinding particles(Engler, 1985; Middelberg, 1995)

Basic Steps of SCP production:

• Preparation of suitable medium with suitable carbon source.

• Cultivation of suitable strain of microorganisms

• Prevention of contaminations• Separation of microbial biomass

with or without product.

General process for production of SCP

1) It requires pure culture of chosen organism that is in the correct physiological state, sterilization of the growth medium which is used for the organism, a production fermentor which is the equipment used for drawing the culture medium in the steady state, cell separation, collection of cell free supernatant, product purification and effluent treatment.

2) A fermentor is the instrument, which is set up to carry out the process of fermentation.

3) Fermentor is also equipped with an aerator, which supplies oxygen to aerobic processes also a stirrer is used to keep the concentration of the medium the same.

4) A thermostat is used to regulate temperature and a pH detector and some other control devices, which keep all the different parameters needed for growth constant.

5) For the producing and harvesting of microbial proteins cost is a major problem. Such a production even in high rate causes dilute solutions usually less than 5% solids. There are many methods available for concentrating the solutions like filtration, precipitation, centrifugation and the use of semi-permeable membranes. The equipment used for these methods of de-watering is expensive and so would not be suitable for small scale productions and operations. Single cell proteins need to be dried to 10% moisture or they can be condensed and denatured to prevent spoilage.

Rudravaram et al.,(2006)

Raw material

Organism Scale Product Organization

Cheese whey Kluyveromyces fragilis 5000

tons/yearFood yeast

fermentation nutrient

Universal Foods Corporation,

Juneau, Wisconsin

Ethanol Candida utilis 10,000 tons/year

Torula yeast, food ingredient

Pure culture products,

Hutchinson, Minnesota

N-paraffins Candida guillienmondis20,000 to

40,000 tons/year

Food yeast

All Union Research

Institute of Protein

Biosynthesis,USSR

Sulfite waste liquor

Candida utilis 15 tons/year Torula yeast

Rhinelender paper

corporationRhinelender Wisconsin

Raw material

Organism Scale Product Organization

Glucose (Food Grade) Fusarium graminearium 50-100

tons/yearMycoprotein

(human food)

Ranks Hovis Mc Dougall, High Wycombe,UK

Cheese whey Penicillium cyclopium 300 tons/year Animal feed Heurty , S.A.,France

Coffee waste Trichoderma harzianum 40,000 lit Animal feed ICAITI,Guatemala and El Salvador

Sulfite waste liquor Paecilomyces varioti

10,000 tons/year

Animal feed(Pekilo

protein)

Tampela and Finnish Pulp and paper

Research Institute,Jamsankosk

i, Finland

Pulp mill wastes Chaetomium cellulyticum 1 tons/day Animal

feed(Waterloo process)

Envirocon Ltd,Vancouver, BC,

Canada;University of Waterloo,Ontario

Organism Raw material

Production Producer or developer

Chlorella sp. CO22 metric tons/day

Taiwan Chlorella Manufacture Co.Ltd, Taipei

Scenedesmus acutus CO2,Urea

20 grams/square

meter/day

Central Food Technological Research

Institute,Mysore,India

Spirulina maxima

CO2, or NaHCO3,Na2CO3

320 metric tons/year

Sosa Texococo,SA Mexico City

• The microbial biomass can be harvested by a variety of methods. • Single cell organisms like yeast and bacteria are normally recovered

by centrifugation, flocculation and floatation.• Filamentous organisms are recovered by filtration. It is important to

recover as much water as possible prior to final drying. • The whole operation is to be done under clean and hygenic

conditions to keep the product and the broth that leaves the plant free of bacterial contamination.

• The final dried products are normally bacteriologically stable if handled properly.

• In some cases, an after-treatment of the biomass is desirable to reduce the unwanted compounds in the product or to isolate the protein.

• One of the important tasks is to reduce nucleic acid content, which is high in microorganisms (4-6% in algae, 10-16% in bacteria, 6-10% in yeasts and 2.5-6% in fungi) and can be hazardous to health.

Biomass Harvesting

i. products obtained via microbiological synthesis must be competitive with traditional food sources.

ii. When estimating costs involved in SCP production, such major factors as the biomass yield, cooling, and oxygen requirements should be taken into consideration.

iii. They depend not only on the choice of substrate, but on the choice of the microorganism as well. All this determines the cost of production and economic feasibility.

iv. It is obvious that one of the major factors limiting the use of hydrocarbon yeast is the residual hydrocarbon content.

v. Demands of the country or its separate regions for protein of a particular type

vi. expenditures for the delivery of finished products to the places of their consumption

vii.Disposal of by products.

Economic parameters : The Scope of SCP production

• Raw materials used in production of SCP are the main safety hazard.

•The acceptability of SCP when presented as a human food does not

depend only on its safety and nutritional value but also the mind

frame of people to consume material derived from microbes which is

concerned to social and ethical issues like psychological, sociological

and religious implications.

•A more intensive clinical and toxicology testing including short-term

acute toxicity testing (animal species) and followed by extensive and

detailed long term studies.

•And in return incurs a huge scientific and financial investment.

ACCEPTABILITY OF SCP AS A HUMAN FOOD AND ITS TOXICOLOGY CONCERN

 The ET Process plant in Fresno, CA, owned by Cottonwood Creek Biosystems, takes in tankered grease and

food processing wastes and generates

single cell protein and dischargeable

water.

Sample of the single cell protein biosolids after the drum dryer.

Table represents the results of total biomass weight and the percentage of protein of mycelial biomass of Penicillium expansum grown on 0.6NH2SO4 pretreated agricultural wastes. The higher amount of single cell protein (1.64 g/L) with higher percentage of protein content (18.25%) was produced by Penicillium expansum when grown on 0.6N H2SO4 pretreated rice husk. Khan(2010)

Wt. of Biomass Broth Protein Reducing Sugar % of Protein

Agricultural wastes Final pH G/Litres mg/ml mg/ml (Nx6.25)

Sugar cane Baggase

5.13 0.3169 0.32 0.45 15.53

Orange peel 5.03 0.3142 0.40 0.58 09.89

Wheat straw 5.80 0.3190 0.32 0.37 06.48

Cotton seeds 6.80 0.4205 0.24 0.20 16.66

Cajanus cajan seeds

6.02 0.5344 0.35 1.26 10.94

Castor been 6.68 0.3277 0.33 0.085 11.62

Rice Husk 7.60 1.64 0.25 0.86 18.25

TABLE : 8

Effect of different agricultural waste material(Pretreated with 0.6N H2SO4)as a carbon source on the production of single cell protein by Penicellium expansum

when cultural grow for 24 hours with initial pH 4.0 at 28±2°C

The protein produced by Candida langeronii in the bagasse hemicellulose hydrolysate contains most of the amino acids essential for animal feed and its quality is comparable to soy bean protein . Its high lysine and threonine content suggest that this yeast protein should be utilized as a feed supplement, specially in diets based on cereals (Kihlberg 1972).

Nigam (2000)

TABLE : 11

The main components of the feed for cultured marine animals in China are microalgae and fish meal. However, production of microalgae and fish meal on large scale is facing many problems due to the contamination and the limited bioresources. Marine yeasts would be better candidates for marifeed production according to their easy cultivation in the fermentor, high cell density, and high content of essential amino acids. Therefore, more than 300 marine yeast strains were evaluated for SCP production in this study. The yeast Cryptococcus aureus G7a strain which was isolated from sediment of South China Sea was a better candidate based on its cell growth (10.1 g/l), the crude protein content (53.0 g per 100 g of cell dry weight), and the wide range of carbon sources used by it.

Essential Nonessential EAAI

Arg His Ile Leu Lys Met Phe Pro Thr Val Ala Asp Cys Glu Gly Ser Tyr0.98

4.35 1.59 5.46 9.09 12.6 3.13 3.16 2.4 4.73 7.17 6.09 8.2 3.11 15.7 6.47 4.04 2.7

Time course of cell growth (open square), SCP production (filled square), reducing sugar (diamond), and total sugar (filled triangle) during the 2-l fermentation by the G7a strain. Data are given as means ± SD, n = 3. The media: the seawater containing 6.0 g of wet weight of Jerusalem artichoke extract per 100 ml of medium and 4.0 g of the hydrolysate of soybean cake per 100 ml of medium; incubation time: 4 days; pH: 5.0; temperature: 28°C; aeration level: 6 l/min; agitation: 200 rpm

EAAI (Feng and Zhao 1997). Values of about >0.95 indicate high quality; about 0.86–0.95 good quality; about 0.75–0.86, useful; about ≤0.75, inadequate.

in the application of 100% concentration (MediumIX), first adult was observed at

the 8th day after mating. That is, metamorphosis was completed

one day ago in this medium. On the other hand, it was also observed

that the body sizes of larvae of experimental groups, especially of 75 and 100% concentrations, were bigger

than those of control. Uysal et al., (2002)

Third instar larvae of D.melanogaster X 31.25

Umphan et al., (2009)

The gain in weight of fish from all treatments of male group was higher than female group and treatment with 3% SP. However, it was highest in treatment control in female group but non-significantly different.

Single cell proteins have application in animal nutrition as:fattening calves, poultry, pigs and fish breadingin the foodstuffs area as: aroma carriers, vitamin carrier, emulsifying aids and to improve the nutritive value of baked products, in soups, in ready-to-serve meals, in diet recipes andin the technical field as: paper processing, leather processing and as foam stabilizers.

Medicinal uses of Spirulina•Strengthen and improve immune system•Phycocyanins build blood cells•Increase antiviral activity•Exhibits anti cancer activity•The US Olympic teams take spirulina tablet as a source of instant energy.Studies showed that spirulina consumption of 4 weeks reduced serum cholestrol level in human beings by 4.5%(Henrikson 1994) and significantly reduced body weight by 1.4±0.4 kg after 4 weeks(Becker et al 1986) There is no changes in clinical parameters (Blood Pressure) or in biochemical variables (haematocrit, haemoglobin, blood cells, sedimentation rate) and absence of adverse effects. The reduction of cholesterol is partly due to high content of gamma linolenic acid in cyanobacteria(Henrikson 1994).

Formulation of SCP

Biolipsticks and herbal face creams are produced in Japan from the phycocyanin pigment of Spirulina.

•Generally, single-cell protein is initially produced as a wet paste and then is subsequently converted into dry powder form. •One of the advantages of the powder formulation is a higher chemical stability than the solution.•This dry powder, similar in appearance and feel to flour, lacks the texture and food-like sensation to the mouth necessary to make an attractive food.• Moreover, when placed in water, the powdered single cell protein rapidly reverts back to single-cell form.•To overcome this disadvantage, we can convert our obtained SCP to other edible form like chocolate.•Chocolate powder serves multiple purpose of cross linking agent, taste maker, and flavouring agent.•Liquid chocolate can also be used for the same. Within economic constraints some other flavouring agents or fruits can be used.•Flavouring agent should be such that it adds to the nutritive value along with taste and fragrance. Chocolates are consumed by people of all ages from childhood to adulthood.• In any stage of life, protein intake is necessary so converting SCP to chocolate form will increase the consumption of protein.

Single celled protein (SCP) production, referring to the fact that most of the micro-organisms used as producers grow as single or filamentous individuals rather than as complex multi-cellular organism such as plants or animals.

Use of microbes in the production of proteins gives many advantages over the conventional methods.

Microbes have shorter generation time, allow easy transformation, utilize many substrates, have no requirements in arable land or any particular season to grow and have the possibility of continuous production in any part of the world.

The cell yield varies according to the substrate and type of microorganism.

Conclusion

For future success of SCP

First, food technology problems have to be

solved in order to make it similar to familiar foods and

Second, the production should compare

favourably with other protein sources.